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Finding the Fourth Proportional to 21,980, 30,330.57 and 12,420.71

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Solution

The fourth proportional to 21,980, 30,330.57 and 12,420.71 is: 17,139.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    21,980 : 30,330.57 = 12,420.71 : x
  2. Step 2: Convert to fraction form
    21,980/30,330.57 = 12,420.71/x
  3. Step 3: Cross multiply
    21,980x = 30,330.57 × 12,420.71
  4. Step 4: Simplify right side
    21,980x = 376,727,214.10
  5. Step 5: Solve for x
    x = 376,727,214.10/21,980
  6. Step 6: Final answer
    x = 17,139.55

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.